Add hot key for align to axis?
Save this to a .py file and install it as an addon



import bpy

bl_info = {
    "name": "Scale 0 Operators",
    "author": "Jan Kadeřábek",
    "version": (1, 0),
    "blender": (2, 7, 0),
    "location": "",
    "description": "",
    "category": "User",
}

class scale_x_0(bpy.types.Operator):
    bl_idname = "view3d.scale_x_0"
    bl_label = "Scale X 0"

    def execute(self, context):
        bpy.ops.transform.resize(value=(0, 1, 1))
        return {"FINISHED"}

class scale_y_0(bpy.types.Operator):
    bl_idname = "view3d.scale_y_0"
    bl_label = "Scale Y 0"

    def execute(self, context):
        bpy.ops.transform.resize(value=(1, 0, 1))
        return {"FINISHED"}

class scale_z_0(bpy.types.Operator):
    bl_idname = "view3d.scale_z_0"
    bl_label = "Scale Z 0"

    def execute(self, context):
        bpy.ops.transform.resize(value=(1, 1, 0))
        return {"FINISHED"}


def register():
    bpy.utils.register_class(scale_x_0)
    bpy.utils.register_class(scale_y_0)
    bpy.utils.register_class(scale_z_0)


def unregister():
    bpy.utils.unregister_class(scale_x_0)
    bpy.utils.unregister_class(scale_y_0)
    bpy.utils.unregister_class(scale_z_0)



This will allow you to set a shortcut for each "scale 0" action.

So after enabling the addon, navigate to User Preferences -> Input -> 3D View -> 3D View (Global) and add shorcuts by inserting corresponding operators, i.e. for scale X = 0, enter view3d.scale_x_0:



It should work for UV editor too, just assign the shortcuts again in Input -> Image -> UV Editor.